Tail recursion in linked list


I had a problem yesterday with a linked data-structure that looked like this:

class ItemRow(private val nextRow: ItemRow?) {
    fun pushOverflow(width) {
        // work on this row


The last line quickly lead to a stack-overflow. I solved it by calling the method from outside, but is there a way to mark this function as tail-recursive?


Have you tried to use tailrec as explained here https://kotlinlang.org/docs/reference/functions.html#tail-recursive-functions ? Does it work for you?


Yes, it tells me that tailrec can’t be applied since the method isn’t calling itself, but the same method on the next object in the chain.


You are right. It is not supported yet. There is a CR about that: https://youtrack.jetbrains.com/issue/KT-15341


Is there a way to use an extension method instead? That would essentially be a single function, so it could be made tail recursive. It doesn’t allow you to use inheritance, but it doesn’t look like you are anyway.


I guess you can write it like this:

class ItemRow(var nextRow: ItemRow?)

tailrec fun ItemRow.pushOverflow(width: Int) {